In operations for injecting fluids, such as injecting biomass for remediation, injection has typically been accomplished by using a hollow-core drill rod, such as a 1 to 2 inch diameter drill rod, with a disposable tip. The drill pipe is pushed into the soil using a direct-push system. In an attempt to avoid clogging, the drill pipe is pushed to the desired depth with a disposable tip. The drill pipe is withdrawn upward a few inches with the tip left in place. Then, injection of the biomass is begun, e.g. at a rate of approximately 5-20 gallons/minute, followed by withdrawal of the pipe upwards, e.g. from about 2 ft. to about 10 ft., and then a repeat of the injection. The operation is continued over the vertical zone to be treated.
A common occurrence is that, when the flow of fluids such as biomass is discontinued, in order to pull the drill string upward or add more drill string or change connections, there is a backflow of fluidized soil and water into the injection ports and hollow drill pipe. This backflow clogs the injection ports and the pipe with soil particles. At this point, restarting the injection is impossible without withdrawing the drill string, clearing the soil plug or replacing the pipe, and starting over. In the field, slurry injection operations often suffer significant downtime, restricted operations, and failure due to this backflow of soil. Presently, there does not seem to be any tool available in technology relating to injecting fluids which addresses this problem.
In addition, there is a need for a system that permits the operator to inject every few feet starting, for example at the top of a water table and moving downward, or to move up and down. The current technology requires injection only as the drill pipe is withdrawn. A typical patented direct-push technology for environmental soil sampling is called Geoprobe™ and there are a number of commercially available sampling and injection systems available that use that technology.
U.S. Pat. No. 4,449,856 relates to grout injection. It discloses an injector design with some helpful features, but it contains numerous parts. In addition, it appears that the injecting pipe can be raised a little at a time, but cannot be moved up and down while injecting. U.S. Pat. No. 4,449,856 discloses an apparatus for injection which comprises an inner pipe member and an outer pipe member having one or more injection orifices formed in the sidewall thereof. It further comprises a first passage formed at a peripheral portion of said injection pipe in parallel with an axis of the pipe, a second passage formed in said inner pipe member, a spool valve fitted in said inner pipe member and biased toward the base side of said injection pipe, one or more exit ports which are formed in a sidewall of said inner pipe member and adapted to be closed normally and communicate with said second passage when said spool valve is displaced towards the tip side of said injection pipe, against a biasing force thereof, upon application of a fluid pressure upon said second passage, and an annular mixing chamber formed between said inner and outer pipe members so as to communicate with said one or more injection orifices and said one or more exit ports. This apparatus is designed to permit mixing before injection and contains numerous parts, including a ball type check valve and a spool valve.
U.S. Pat. No. 4,859,119 discloses an apparatus for grout injection which includes a valve moved by a spring. In part it discloses a piston valve vertically movably received in an upper portion of a third channel and having a piston upwardly of said lower communication holes, said piston valve being urged to be normally raised by means of a spring; whereby when said piston valve is raised, said upper communication holes and upper discharge holes are closed by said piston and concurrently said second channel is permitted to communicate with a lower portion of said third channel through said lower communication holes and when said piston valve is lowered, said upper communication holes and upper discharge holes are opened and concurrently said second channel is prevented from communicating with said lower portion of said third channel through said lower communication holes. This grouting rod has multiple moving piston valves. With communication holes always open to the soils/sands/aquifer, this unit becomes susceptible to backflow of soil and clogging. With the piston in the upper or lower position and the opposite communication holes left open without any liquid exiting these holes under pressure then these holes may become a pathway to completely disable this unit because of flowing soil clogging the entire portion that is left exposed. In addition, in the event that a few grains of sand get lodged between the piston and channel may cause the piston to become jammed and cease functioning.
In the art of injecting materials, of any type of slurry, including but not limited to biomass, chemicals, grout, oxidants, slurries for agricultural or remediation purposes, there is a need for a rugged type of injection tool that can be moved up or down while injecting and in addition to having a means for preventing backflow of soil and other materials into the injection pipe while not pumping or making changes to the drill string or pump/hose attachments to the drill string. In addition, due to the nature of such operations, i.e. operating at different soil depths and in different types of soil, it would be extremely desirable if such an apparatus had minimal moving parts that were protected from contact with the soil and permitted easy cleaning. It would also be extremely desirable if the design of the apparatus permitted maintenance of a fluid or slurry column in said drill pipe within the in-soil hollow drill pipe while pump connections and injection pipe extensions were changed at the surface. It would also be preferable to use a permanent tip and not have the expense of constantly replacing disposable tips. In the process of trying to solve these problems, we discovered a design for an apparatus that would accomplish these objectives.